Mar 24, 2021
Volcanologist explains what causes a volcano to erupt in 6 levels of difficulty
I am a volcanologist with expertise in magmatic plumbing and here is a very common question with answers based on my audience:
What causes a volcano to erupt?
To the very young child: Lava makes a volcano erupt. It’s rising up out of the ground and it needs to come out somewhere. Bam, volcano! Are you still with me? Oh… no, you’re already on the jungle gym? Ok.
To the elementary school student: I used to give volcano talks to elementary schools so this is an easy one. You need to have magma, but you also need to have gases dissolved in it and when the bubbles come out of the magma, they explode, just like a shook-up bottle of soda! And if the magma is hard, it explodes violently and if it is really liquid, it can be like Hawaii. How cool is that?! Is everyone still with me?
To the teenager who’s actually interested in science: I list the major factors that influence an eruption, rather halfway between what I did for the gentleman from the church above and the non-geologist academic. I try to give them a glimpse of the incredible complexity involved and the excitement in studying it without overwhelming them. Check to see if they’re still with me.
To the nice gentleman at church whose next question is probably about Yellowstone… because that’s everyone’s next question… always: I spend about a minute and a half telling him that the chemistry of the magma and the gases in it are what lead to an eruption, compare and contrasting Hawaii to an explosive volcano very briefly and then checking to see if he’s still with me.
To a scientist or highly educated academic who is not a geologist: I spend about 7 or 8 minutes summarily discussing/listing the role of magma chemistry, silica content and polymerization, water and gas content and magma chamber characteristics and then check to see if they’re still with me.
To a trained geologist: I go on for at least 20 minutes about fractional crystallization within magma chambers, gas exsolution, thermodynamics, phreatomagmatic interaction (particularly in terms of groundwater and overburden alteration) and then check to see if they’re still with me.
